In this Jan. 12, 2009 file photo, the General Motors logo is seen on display at the North American International Auto Show in Detroit. Congress, the Justice Department and the National Highway Traffic Safety Administration are all investigating General Motors Co.’s recall of 2.6 million vehicles for an ignition switch defect which can cause the car to stall and deactivate the air bags. GM links the defect to 13 deaths and more than two dozen crashes.(AP Photo/Paul Sancya, File)

WASHINGTON (AP) — Lawmakers on Capitol Hill accused General Motors of a potentially criminal cover-up of its defective ignition switches and fumed at the lack of answers from its new CEO during a second day of hearings Wednesday into why GM waited a decade to recall cars with the deadly flaw.

Members of a Senate subcommittee also said GM should tell owners of the 2.6 million cars being recalled to stop driving them until they are repaired. But CEO Mary Barra gave assurances that the cars, mainly Chevrolet Cobalts and Saturn Ions, are safe to use while owners wait for the replacement part, saying she would let her own son get behind the wheel if he took certain precautions.

GM has linked the switch to 13 deaths and dozens of accidents. Others, including relatives of some victims, have a higher count of fatalities.

The automaker has said the ignition switch can move from the "run" position to the "accessory" position because of weight on the key chain. That causes the engine to shut off, disabling power steering, power brakes and the front air bags.

As she did Tuesday at a House hearing, Barra said many of the answers Congress is seeking will come out in an internal GM investigation that should be completed in 45 to 60 days. She also said she was unaware of certain details about GM's handling of the problem — an assertion that frustrated some of the senators.

Barra also tried to assure lawmakers that GM is now more focused on safety and the consumer. Few sounded convinced.

"If this is the new GM leadership, it's pretty lacking," Boxer said.

Senators aggressively questioned Barra about how GM approved a replacement switch in 2006 but never changed the part number. Failing to change the number makes the part harder to track. In this case, anyone investigating the cars wouldn't know why earlier switches were failing at a higher rate than later ones.

While Barra called the failure to change the part number "unacceptable," several members of the panel implied that it was done intentionally by a person or group within the company.

"I don't see this as anything but criminal," said Sen. Kelly Ayotte, R-N.H., a former prosecutor.

Sen. Richard Blumenthal, D-Conn., who is also a former prosecutor, told Barra that the more he learns about GM, "the more convinced I am that GM has a real exposure to criminal liability."

The Justice Department is conducting a criminal investigation of GM's handling of the recall. Barra promised the company will cooperate.

Barra said the company has not yet fired any employees in connection with the recall. But she said if inappropriate decisions were made, GM will take action, including firing those involved.

As she began her testimony, Barra faced an angry and skeptical Sen. Claire McCaskill, D-Mo., the head of the subcommittee, who recounted the story of a woman who died in an accident involving a faulty switch.

McCaskill said GM had "a corporate culture that chose to conceal rather than disclose."

McCaskill also dismissed Barra's claim that there is a new culture at GM. She said that when emerging from bankruptcy in 2009, GM had ample time to recall cars with the faulty switch.

GM did not begin recalling the vehicles until February.

Blumenthal said GM should immediately tell owners of the recalled cars not to drive them until they're repaired because they're unsafe. GM plans to begin repairing the cars this month but has said it might take until October to get them all fixed.

Barra said GM has already provided 13,000 loaner cars to drivers who are concerned. But she said the company's testing on different types of roads shows the cars are safe as long as there is nothing but the ignition key on the key chain.

"I would allow my son and daughter — well, my son, because he's the only one eligible to drive — if he only had the ignition key," she said.

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